D1-class dopamine receptors influence cocaine-induced persistent expression of Fos-related proteins in striatum

CHRONIC intermittent exposure to psychomotor stimulants induces in the striatum the expression of Fos-related proteins (Fras) that persist after the end of drug treatment. We carried out experiments to determine whether such Fras ('chronic Fras') require dopamine D1-class receptor function for their persistent expression in the striatum. We chronically administered cocaine to rats in a behavioral sensitization protocol and blocked D1-class receptors with SCH23390 before a final cocaine challenge. Western blotting and immunohistochemical analyses indicate that Fras persistently expressed in response to chronic treatment include proteins of two types: those that have become independent of D1-class dopamine receptor activation and those that remain dependent on D1-class receptors for their expression following drug challenge.